Project Manager's Wiki | Glossary / Inter-task Dependencies

Inter-task dependencies exist when the start or completion of one task is related to start or completion of another one.

There are three types of dependencies:

Finish-Start
Start-Start ?
Finish-Finish

The task that must be perfomed first are “predecessor tasks” and those that follow are “successor tasks”.

Finish-Start.
This is the most common dependency relationship. The predecessor task must finish before the successor task can start.

Start-Start.
The predecessor task must start before the successor task can start.

This relation if often erroneously interpreted as meaning that both tasks start at the same time. As an example is a situation that controlling project flow must have started after the project itself started.

Finish-Finish.
The predecessor task must finish before the successor task can finish.

As an example, coding must finish before testing can be completed.